Rubies: World's Most Valuable Gem

     Rubies are a red variety of the mineral corundum. Pure corundum (a form of aluminum oxide) is colorless, but different impurities can alter the mineral’s color. Rubies are turned red by impurities of iron and chromium. Rubies can be any shade of red including pink, purple, and reddish brown, but a bright red is the most desirable. Ruby crystals usually form as hexagonal prisms with flat or tapered ends. However rubies are not always found as these perfect prisms, but as rounded pebbles in gem-rich gravels in gravel pits and river beds. Ruby crystals often form crystal twins when they grow naturally and will sometimes fracture because of it. Crystal twinning is a term used to describe a growth pattern in crystals in which two or more crystals appear to intersect one another symmetrically. Other than twinning rubies are also known to display what is called asterism. Asterism is a phenomenon that occurs in some crystals because of the stones’ internal features such as cavities or fibrous crystal inclusions. When the light reflects off of these cavities or crystals a star shape appears in the stone (this is most visible when the stone is cut en cabochon --cut and polished with a domed surface like a lens) When a stone has two sets of parallel crystals a four-rayed star is produced. When there are three sets of parallel crystals present a six-rayed star is produced (this continues onward!) Rubies also display what is called zoning. Ruby crystals grown in layers and sometimes the layers can be different shades of the same color. When different color variations are present in the same crystal this is called zoning.
     Rubies are a rare and valuable type of gemstone so they are used mostly in jewelry. Rubies are very hard (second only to diamonds in their hardness), they are a very attractive color, and are quite rare, so they are good candidates for the gem industry. This may be hard to believe, but gem quality rubies are actually the most valuable gemstone in the world, worth more than diamonds of the same size! Besides gemstones rubies have some industrial uses. Because they are so hard, tiny rubies or very small pieces leftover from gem cutting are used to make emery boards and some kinds of sandpaper (or emery cloth). Rubies are also used in medical lasers and some watches.
     Rubies that are not of gem-quality are found in many parts of the world, but true gem-quality rubies are found only in certain places. Myanmar is probably the most historical source, but nowadays most rubies come from Thailand. Most Thai rubies are brownish red in color. The best bright red rubies come from Afghanistan, Pakistan, and Vietnam. Opaque rubies are found in Norway, Russia, India, Australia, and North Carolina. I think that their beautiful red color can be a reminder of the undeserved gift of our Savior’s blood that was spilled on our behalf. With this in mind one can think that rubies are very special stones!